Changes in intracellular enzyme kinetics and metabolic compartmentation associated with carcinogen treatment and spontaneously or chemically induced neoplastic transformation will be investigated by microspectrofluorometry. The intracellular binding, accumulation and metabolites of recently synthetized carcinogens (of the chrysene or benzanthracene series) will be investigated. Studies will be carried out in El2, L, NCTC 8739 cells, paired lines of normal vs. spontaneously transformed cells, hepatomas of graded malignancy, neuroblastoma). The living cell represents an organizational complex with a delicate control of simultaneously operative pathways, and compartments. On this basis, topographic analysis of fluorescence transients (e.g. NAD(P) yields (reversibly) NAD(P)H) will be carried out on 50-100 cell sites simultaneously (following intracellular electrophoretic injection of metabolites), in ref. to mitochondrial-extramitochondrial dehydrogenase and shuttle pathways, regional asynchronicities. The cell fluorescence spectrum will be resolved in free vs. bound NAD(P)H, flavoproteins, and correlated to distribution or induction of dehydrogenases. The living cell will be submitted to challenges which may alter the regulation of intracellular pathways or organelles, e.g.: carcinogens, growth with various substrates, agents affecting mitochondrial-cytoplasmic-nuclear exchanges or organelle biogenesis. Fluorescence spectra of carcinogen (or metabolite) treated cells using a high temporal and spectral resolution microspectrofluorometer may lead to in situ detection of carcinogen interactions and metabolites in localized cell regions. Via the intracellular assay of carcinogens, carcinogen-metabolizing activity and definition of metabolic aberrations (promoting the action of carcinogens or carcinogen-induced) ultimately methods may be developed for predicting the susceptibility of cell lines to malignant growth or recognizing early metabolic criteria of malignant transformation.